Short answer: the ThieAudio Monarch MKIII. It ranks #1 of 238 in-ear headphones by sound quality (rated 4.9/5); the ThieAudio Monarch MKII ranks #44 (rated 4.6/5).
The case for the ThieAudio Monarch MKII: A preference score of 81 from crinacle’s measurement and just 1.45 dB of deviation make it one of the most accurate in-ears available. The catch: Those measurements show a 5.6 dB dip near 6.5 kHz and treble about 2.6 dB below target, which softens cymbal attack slightly.
The ThieAudio Monarch MKIII is the better-sounding option. A preference score of 91 in HypetheSonics’ measurement, with an exceptionally smooth 0.77 dB standard deviation from target. The catch: The air band from 10 to 16 kHz sits about 5.7 dB above target with a 4.4 dB peak near 11.9 kHz, which can add a hint of glare on bright or sibilant recordings.
Buy the ThieAudio Monarch MKIII. It is rated higher for sound quality than the ThieAudio Monarch MKII.
Still deciding? The full Headphones rankings cover every ranked option.
Specifications Side By Side
| ThieAudio Monarch MKII | ThieAudio Monarch MKIII | |
|---|---|---|
| Price | - | $999.00 |
| Ranked | #44 of 238 in In-Ear Headphones | #1 of 238 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 81 (measured by crinacle, via AutoEQ) | 91 (measured by HypetheSonics, via AutoEQ) |
| Deviation From Target | 1.45 dB standard deviation | 0.77 dB standard deviation |
| Tonal Tilt | -0.22 (negative is warmer, positive brighter) | -0.11 (negative is warmer, positive brighter) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 6 balanced armature + 2 electrostatic) | Hybrid (2 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 1 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic | 2 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Impedance | 36 ohms | 18 ohms |
| Sensitivity | 108 dB/mW | 99 dB @ 1kHz |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) | 20Hz - 80kHz (Manufacturer specified) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.3 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.8 dB at 30 Hz) |
| Built-in Microphone | - | No |
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Prices on this page were last checked October 10, 2026 at 5:37 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Headphones In Full
ThieAudio Monarch MKII AliExpress eBay
Pros: A preference score of 81 from crinacle’s measurement and just 1.45 dB of deviation make it one of the most accurate in-ears available. Across 19 hobbyist measurements on squig.link, sub-bass and bass sit within half a dB of target down to 20 Hz, so kick drums and synth bass have full, tight weight. Its 108 dB/mW sensitivity and 36 ohm impedance mean a phone drives it easily, and the hybrid layout combines a dynamic woofer, six balanced armatures and two electrostatic tweeters.
Cons: Those measurements show a 5.6 dB dip near 6.5 kHz and treble about 2.6 dB below target, which softens cymbal attack slightly. Air above 10 kHz rises about 3.4 dB over target, peaking near 11.8 kHz, which listeners sensitive to treble may hear as a touch of glare.
Full ThieAudio Monarch MKII review and specifications →
| Released | Oct 2021 (5 years ago) |
|---|---|
| Back | Closed |
| Connection | Wired |
| Deviation From Target | 1.45 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 1 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) |
| Harman Preference Score | 81 (measured by crinacle, via AutoEQ) |
| Impedance | 36 ohms |
| Sensitivity | 108 dB/mW |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.3 dB at 30 Hz) |
| Tonal Tilt | -0.22 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -3.6 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | +0.1 dB | 0.70 |
| Peak | 6,833 Hz | +3.8 dB | 2.05 |
| Peak | 2,005 Hz | -1.3 dB | 1.08 |
| Peak | 319 Hz | -0.9 dB | 1.20 |
| Peak | 9,387 Hz | +2.0 dB | 3.00 |
| High shelf | 10,000 Hz | -2.6 dB | 0.70 |
| Peak | 4,445 Hz | +2.7 dB | 6.00 |
| Peak | 5,134 Hz | -2.0 dB | 6.00 |
| Peak | 811 Hz | +0.4 dB | 2.29 |
| Peak | 81 Hz | +0.3 dB | 1.93 |
- Reviews, Comparisons and Sound Samples
ThieAudio Monarch MKIII: $999.00 Linsoul eBay
Pros: A preference score of 91 in HypetheSonics’ measurement, with an exceptionally smooth 0.77 dB standard deviation from target. Everything from 20 Hz to 10 kHz stays within about 1.1 dB of target, so bass, vocals and treble all sound balanced and true. It rates above the pricier Symphonium Audio Helios and well above the SoftEars RSV.
Cons: The air band from 10 to 16 kHz sits about 5.7 dB above target with a 4.4 dB peak near 11.9 kHz, which can add a hint of glare on bright or sibilant recordings. It is a wired in-ear with no built-in microphone, so it is not suited to calls on the go.
Full ThieAudio Monarch MKIII review and specifications →
| Released | 2023 (3 years ago) |
|---|---|
| Back | Closed |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 0.77 dB standard deviation |
| Driver Type | Hybrid (2 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 2 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 80kHz (Manufacturer specified) |
| Harman Preference Score | 91 (measured by HypetheSonics, via AutoEQ) |
| Impedance | 18 ohms |
| Sensitivity | 99 dB @ 1kHz |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.8 dB at 30 Hz) |
| Tonal Tilt | -0.11 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -1.0 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | -0.1 dB | 0.70 |
| Peak | 742 Hz | +1.1 dB | 1.13 |
| Peak | 130 Hz | -1.1 dB | 1.51 |
| Peak | 1,584 Hz | -0.6 dB | 1.19 |
| Peak | 3,281 Hz | +0.9 dB | 4.08 |
| High shelf | 10,000 Hz | -7.9 dB | 0.70 |
| Peak | 8,077 Hz | +1.8 dB | 1.48 |
| Peak | 5,639 Hz | -1.4 dB | 6.00 |
| Peak | 9,669 Hz | +1.1 dB | 4.55 |
| Peak | 60 Hz | +0.1 dB | 2.11 |
- Reviews, Comparisons and Sound Samples